Grinding machine



June 30, 193-1;

M. 1. MATHEWSON ET AL 1,812,444

GRINDING MACHINE Filed June 22. 1927 2 Sheets-Shet 1 Patented June 30, 1931 4 UNITED STATES PATENT OFFICE MAXWELL I. MATHEWSON, F PROVIDENCE, AND ARTHUR BROWN, 01 CRANSTON, RHODE ISLAND, ASSIGNORS TO BROWN AND SHARPE MANUFACTURING COMPANY,

.A CORPORATION OF RHODE ISLAND GRINDING MACHINE Application flled J'une 22, 1927. Serial No. 200,628.

The invention relates to grinding machines.

The primary object of the invention is to improve and simplify the construction and operation of certain portions of a grinding machine and particularly the construction of the wheel spindle bearings.

With this object in view, the several features of the invention consist in the devices, combinations and arrangements of parts hereinafter described and claimed and together with the advantages to be obtained thereby should be readily understood by one skilled in the art from the following description taken in connection with the accompanymg drawings.

, In the drawings, which illustrate one embodiment of the invention in a grinding machine, Fig. 1 is a detail sectional view in front elevation of the grinding wheel spindle and spindle bearings taken on the line 1-1 of Fig. 2 showing the radial and end thrust bearings; Fig. 2 is a view taken on the line 2 2 of Fig. 1; and Fig. 3 is a plan view of the parts shown in Figs. 1 and 2 with the radial thrust bearing caps removed to show the bearing blocks for the spindle.

The preferred embodiment of the present invention in a grinding machine comprises a rotary grinding wheel which is secured to a spindle mounted on'a spindle wheel carriage to move toward and away from the work. Inasmuch as the grinding wheel must be capable of very fine adjustment with relation to the work, and rotates at'comparatively high speeds,'the spindle bearings must be carefully constructed and fitted to prevent any possibility of looseness or play of the spindle, and due to the large'size of the rotating parts and the high speed conditions of operation, it is of particular importance to keep the bearings at all times thoroughly lubricated.

To secure these results, radial and end thrust bearings have been provided for the wheel spindle which may be automatically adjusted by spring means to secure the re quired tightness of fit without at the same time causing the film of lubricating oil to be ruptured with consequent damage to the bearing.

' The radial thrust bearings comprise radial bearing blocks provided at each end with trunnions which engage with radially disposed guideways formed in the fixed portions of the bearings to hold the bearing blocks against movement with the rotating spindle. With this arrangement, the blocks can be moved towards and away from the spindle and may tilt freely about the axes of the trunnions.

The bearing blocks are held in contact with the spindle by means of spring plungers which press against the blocks along the axes of the trunnions and are mounted 1n removable caps to permit ready access by the operator to theparts. After the bearings have been adjusted to secure the desired tightness of fit by the action of the compression springs, the plungers may be clamped rigidly in adjusted position.

In order to prevent the bearings from being wiped dry by the contact of the leading edge of the bearing blocks with the rotating spindle, these blocks are made wider at the leading side of the axis of the trunnions, or the side which the spindle surface is approaching, so that the pressure of the spring plungers is unevenly distributed, the heavier pressure being obtained on the rear portion of the blocks. Thus a comparatively thick oil film is obtained under the leading edge of the block tapering to a comparatively thin film at the rear edge corresponding to the greater pressure there obtained.

Referring more particularly to the drawings,.the grinding machine herein illustrated comprises a grinding wheel 6 secured to rotate on a spindle 8 which is mounted on a carriage 10 movable on the slideways 12Ion the frame 14 towards and away from the work. A work supporting carriage of ordinary construction is slidably mounted on ways to move transversely of the machine. Between the work support and the spindle carriage is a relatively deep trough formed in the frame 14. The spindle 8 is mounted to turn in the fixed bearings indicated at 20 and 22 on the carriage 10 and is held accurately in position by means of the radial bearing blocks indicated at 24, 26, and 28. The grinding wheel is driven through'abelt pulley indicated at 30 on the wheel spindle.

In order that the bearing blocks may be held securely in position while at the same time permitting their ready adjustment with relation to the spindle, and also to facilitate their removal from the machine, they are provided at each end with trunnions 32 which are adapted to engage in radially situated slots 34 in the fixed portions of the bearings. The bearing blocks are held adjustablv in contact with the spindle by compression spring plungers 36 which press against the radial bearing blocks at points which are on a line with the axis of the trunnions 32. With this arrangement, the bearing blocks may be held with uniform pressure in contact with the spindle while permitting the blocks to adjust themselves automatically about the axis of the trunnions to fit the contour of the rotating spindle.

Inasmuch as it is usually necessary for the workman to take out and replace the radial bearing blocks several times in fitting the radial thrust bearings, these parts have been constructed and arranged particularly to make them readily accessible. The plungers for the bearing blocks 24 and 26 are, therefore, mounted in a removable cap 38 which is secured to the machine frame by the screw bolts 40, and the plungers for the bearing block 28 are similarly mounted in a removable cap 42. The compression springs 44, coiled within recesses 46 in the plungers and bearing at their outer ends against the cap 38,. tend to hold the plungers yieldingly in engagement with the radial bearing blocks. The plungers 36 may be locked in the position to which they have been adjusted by the springs 44 by means of friction members 47 mounted in the cap adjacent to the plungers and forced into hard frictional contact therewith by means of the set screws 48 as illustrated in Fig. 2-:

When the radial bearing blocks are applied to the spindle bearings with sufiicient pressure to prevent undesirable movement or chatter of the spindle there in a tendency for the leading edge of the bearing block to wipe the rotating spindle dry of lubricating oil with consequent injury to the parts. This difliculty has been met in the present instance by locating the axis of the trunnions about which the blocks rotate to one side of the center of the block, the wider side being placed on that side of the block which the surface of the rotating spindle approaches so that-the greater part of the pressure exerted by the spring plungers will fall upon the rear portion of the bearing blocks. A comparatively thiclcoil film will'then be-collected under the leading edge of the bearing reducing the danger of wiping the bearing to End thrust bearings are provided for positioning the spindle as accurately as possible against movement lengthwise in either direction, and automatic spring means are provided for adjusting the bearings to secure the required tightness of fit to prevent looseness of the spindle without rupturing the oil film in the bearings. To reduce the effect of expansion and contraction of the spindle to a minimum the bearings for taking up the end thrust in both directions are located at one endof the spindle. The end thrust in one direction is taken up by the engagement of the fixed bearing or bushing 22 with a ring .49 mounted on the spindle between a shoulder 50 and a nut 51 threaded to the end of the spindle. The end thrust in the opposite direction is taken up by means of a bearing block 52 which is slidably mounted in the wheel spindle carriage and is held yieldingly in contact with the spindle by means of a compression spring 54 inserted in a recess 56 in the block to bear against the fixed plate 58. The block 52 may be securely clamped in the position to which it is adjusted by the pressure of the spring 54 by means of a friction member 60 which is forced into contact with the block by means of a set screw 62. The tension of the spring 54 is such as to insure a. suflicient degree of tightness without running the risk of rupturing the oil film in the bearings. After the machine has been sufliciently warmed up, the set screw 62 is tightened up, locking the block 52 in position and' thus substituting a fixed bearing for the yielding spring contact.

The invention having been described, what is claimed is:

1. A grinding machine having, in combination, a grinding wheel spindle and a radial thrust bearing for the spindle comprising a fixed bearing, a radial bearing block, trunnions on the block, guideways engaging therewith to position the block with relation to the fixed portion of the bearing, and .1.

spring means for forcing the block yielding'ly a fixed bearing, guideways formed in the fixed bearing, a radial bearing block mounted to tilt in the guideways and to move toward and away from the spindle, spring means acting on the line of the tilting axis of the block for holding the block yieldingly in engagement with the spindle, and means for locking the block in the position to which it has been adjusted by t e spring means. 10 LA grinding mac me having, in combination, a grinding wheel spindle and radial thrust bearings for the spindle comprising a fixed bearing, a radial bearing block, radially disposed guideways, trunnions'on the block engaging the guideways to permit tilting movement and movements toward and away from the spindle, spring plungersacting on the line of the axis of the trunnions for forcing the block yieldingly into engagement with the spindle, and a removable cap in which the spring plungers are seated.

5. A grinding machine having, in combination, a grinding wheel, a grinding wheel spindle and a radial thrust bearing for the spindle comprising a fixed bearing, a radial bearing block, radially disposed guideways, trunnions on the block engaging the guideways to permit tilting movement of the block and movement towards and away from the spindle, spring pressed plungers acting on-the line of the axis of the trun- -nions to force the block yieldingly into engagement with the spindle, a removable cap in which the plungers are housed, and means for clamping the plungers rigidly in position in the cap.

6. A grinding machine having, in combination, a grinding wheel spindle and a radial thrust bearing for the spindle comprising a fixed bearing, a radial bearing block, radially disposed guideways, trunnions on the ends of the block to engage the guideways, the trunnions being situated to the rear of the center line of the block, and spring means. acting on the line of the axis of the trunnions for forcing the block yieldingly into engagement with the spindle.

4 7. A grinding machine having, in combination, a grinding wheel spindle and a radial thrust bearing for the spindle comprising a fixed bearing, a radial bearing block, radially disposed guideways-,.trunnions on the ends of the block to engage the guideways, and means acting on the block to the rear of the center line thereof for holding the block in operative relation to the spindle.

8. A grinding machine having, in combination, a grinding wheel spindle and a radial thrust bearing for the spindle comprising a fixed bearing, a radial bearing block, radiall disposed guideways, trunnions on the en s of the block engaging the guideways to permit tilting movement and movement towardand away from the spindle, and situ- M ated to leave the larger portion of the bearing surface of the block on the leading side of the axis of the trunnions, spring plungers acting on the line of the axis of the trunnions for forcing the block yieldingly into engagement with the spindle, and means for clamping the plungers in position.

In testimony whereof we have signed our names to this specification.

.MAXWELL I. MATHEWSON. ARTHUR BROWN. 

